Mainship 390 water tanks

[Walkweb]

Scratching my head here. The fresh water tanks on my 2000 Mainship 390 have stopped balancing/leveling. Anyone know how the system works - the Owner's Manual doesn't even mention it? Is the balancing done at the water pump end, or is there a pipe between the two tanks that I can't see? It did happen after I replaced a leaky water pump and tired accumulator. Insight would be greatly appreciated. Thanks.

 

[Bacchus]

Only a guess based on my 2008 MS 34HT with 2 FW tanks.
Mine fills port side only and pump draws from stbd. Connection is via hose between. Each have their own vents / vent hoses.
I haven't noticed a balancing problem but if I did first thing I'd check is whether one of the vents is blocked. My sending unit is on the stbd andvI do noticed a lag in reading when filling.

 

[tiz]

I believe there is a 1/2" water tube between tanks. Look down in the hatch aft of the generator. Mine has white 1/2" whale potable tubing to send water to the pump. Also a t that I believe is the crossover between tanks. The p/s selection valves on mine are near the domestic water pump.

The fills are larger -maybe 1.25" hose with a Y that, when one tank is full, finishes filling the other tank. I dislike the system but there it is.

 

[DrissZougari]

My tanks have two valves on the bulkhead next to the pump. I can select witch tank I am pulling from and that way I can also balance the boat using the water tanks.

 

[mncruiser]

Also look under the guest stateroom berth where the water heater is. On my 2001 390 there are valves there that control which tanks the pump pulls from and I believe the balancing too.

On mine the valves do not operate normally, when one is closed it is actually open. Previous owner (Thanks Bob!) left me notes on this. Unsure if yours is the same.